Abstract
BackgroundThe serious impact effects of persistent organic pollutants such as organochlorine pesticides, especially dichlorodiphenyltrichloroethane family (DDTs) and hexachlorocyclohexane isomers (HCHs) have been causing widespread concern, despite effective control on their manufacturing, agricultural and vector practices. In that, in addition to the previous global limitations on DDTs usage, α-HCH, β-HCH and lindane have also became an on-going topic of global relevance based on the latest Stockholm Convention list on 10th of May 2009. Concentrations of dichlorodiphenyltrichloroethane family (DDTs) and hexachlorocyclohexane isomers (HCHs) were determined by GC-ECD in Cameron Highlands, the main vegetables and flowers farming area in Malaysia as an agricultural tropical environment. A total of 112 surface water and sediment samples at eight points were collected along the main rivers in the area namely Telom and Bertam in the dry and wet seasons of 2011.ResultsTotal concentration of HCH isomers ranged from not detected to 25.03 ng/L in the water (mean of 5.55 ±6.0 ng/L), while, it ranged from 0.002 to 59.17 ng/g (mean of 8.06±9.39 ng/g) in the sediment. Total concentration of DDT and its metabolites in the water samples varied from not detected to 8.0 ng/L (mean of 0.90±1.66 ng/g), whereas, it was in the range of 0.025 to 23.24 ng/g (mean of 2.55±4.0 ng/g) in the surface sediment samples. The ratio of HCHs and DDTs composition indicated an obvious historical usage and new inputs of these pesticides. Among alpha, beta, gamma and delta isomers of HCH, gamma was the most dominant component in the sediment and water as well. Some seasonal variations in the level of selected pesticides were noted.ConclusionsThe results illustrate distribution, behaviour and fate of HCHs, and DDTs have closely connected with topological and meteorological properties of the area beyond their chemical characterizations. The features of environmental circumstances exceed one or more of these characters in importance than the other. Although the results show that the situation is better than 1998, the impact of persistent agrochemicals such as lindane and 4,4′DDE are revealed in a key tropical area of Malaysia.
Highlights
The serious impact effects of persistent organic pollutants such as organochlorine pesticides, especially dichlorodiphenyltrichloroethane family (DDTs) and hexachlorocyclohexane isomers (HCHs) have been causing widespread concern, despite effective control on their manufacturing, agricultural and vector practices
They researchers clearly pointed out that human activities are the main source of contamination by organochlorine pesticides (OCPs), which almost certainly relates to activities such as agricultural chemicals, domestic and industrial discharge, street and road run-off, car exhausts and slum sewage, and other strongly related factors including soil erosion caused by deforestation as well as atmospheric transport [18]
Based on rainfall data in the Cameron Highlands meteorological station records, February, June and July were assigned as a dry season with 50-150 mm monthly average rainfall and April, May, August and November were considered as a wet season with 300-400 mm
Summary
The serious impact effects of persistent organic pollutants such as organochlorine pesticides, especially dichlorodiphenyltrichloroethane family (DDTs) and hexachlorocyclohexane isomers (HCHs) have been causing widespread concern, despite effective control on their manufacturing, agricultural and vector practices. Persistent organochlorine pesticides (OCPs), especially dichlorodiphenyltrichloroethanes (DDTs) and hexachlorocyclohexane isomers (HCHs) cause widespread concern, despite controls on their manufacturing, agricultural and vector practices. They researchers clearly pointed out that human activities are the main source of contamination by OCPs, which almost certainly relates to activities such as agricultural chemicals, domestic and industrial discharge, street and road run-off, car exhausts and slum sewage, and other strongly related factors including soil erosion caused by deforestation as well as atmospheric transport [18]. The 4th meeting of the Conference of Parties agreed to put α-HCH, β-HCH and lindane, on the Persistent Organic pollutants (POPs) list at the Stockholm Convention on 26 August 2009 [3]
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